Melt Strength and Rheological Properties of Biodegradable Poly(Lactic Aacid) Modified via Alkyl Radical-Based Reactive Extrusion Processes

Poly(lactic acid) (PLA) has been modified using twin-screw reactive extrusion to improve its melt properties and crystallinity. In this work lauroyl peroxide was used as an alkyl free radical source, abstracting hydrogen atoms from the PLA backbone leading to branching and chain extension reactions. Once the linear viscoelastic region was determined for these polymers, changes in dynamic rheology (dynamic viscosity real and loss modulus) were measured. Gel permeation chromatography showed that the molecular weight and polydispersity increased to a maximum with the addition of 1.00 and 0.50?wt% peroxide, respectively. Low temperature ?? transitions in dynamical mechanical thermal traces gave further evidence that branching had also occurred. G?ttfert Rheotens measurements showed a three fold increase in melt strength due to both increased chain length and branching. Thermal analysis showed the level of crystallisation had decreased also possibly due to branching. Reductions in crystallinity and improved melt strength are known to be critical for film and foam formation.     

Biodegradable Blends from Corn Gluten Meal and Poly(butylene adipate-co-terephthalate) (PBAT): Studies on the Influence of Plasticization and Destructurization on Rheology,Tensile Properties and Interfacial Interactions

Melt extrusion was used to obtain thermoplastic corn gluten meal (tCGM) blends from plasticized corn gluten meal (pCGM) and poly(butylene adipate-co-terephthalate) (PBAT). Dynamic rheological tests, morphology and spectroscopy were employed to understand the effect of the plasticization and destructurization of corn gluten meal (CGM) on tCGM blends. Rheological data showed a plateau in the low frequencies for tCGM blends demonstrating network formation which responds elastically over long timescales. Also, complex viscosity data showed the existing of shear thinning for PBAT and PBAT–CGM blend. Furthermore, rheology and morphology showed the synergistic influence of plasticization and destructuralization of CGM on the phase structure development of the blends. In addition, it was found for unmodified CGM–PBAT blend there was significant frequency dependence for G′ indicating it just acted as filler for PBAT matrix. FTIR studies showed that the urea has helped in unfolding the corn protein and facilitated hydrogen bonding interactions with PBAT. Tensile properties showed an improvement in tCGM blends when compared unmodified CGM blend. Tensile strength of tCGM blends was almost same as that of the neat PBAT matrix. Percent elongation, a strong reflection of the state of interface in the blends has showed higher values, indicating strong interactions between the PBAT and pCGM in the blend system.     

Development of Proteinous Bioplastics Using Bloodmeal

The aim of this work was to investigate the use of bloodmeal as a thermoplastic biopolymer. Processing required water and chemical additives to perform three main functions: breaking covalent cross-links using sodium sulfite (SS), sodium dodecyl sulfate and urea as processing aids, and evaporating some processing water to allow formation of new interactions to stabilize the final structure. Extrusion was only possible in the presence of SS and strongly influenced by water and urea content. It was found that once water had been removed, mechanical properties increased significantly, indicating the formation of new intermolecular forces. SDS was required for processing and consolidation, but, it may restrict formation of new intermolecular forces, if used in excessive quantities. Materials based on optimal additive levels had a tensile strength of 8 MPa, Young’s modulus of 320 MPa and toughness 1.6 MPa m^½.     

Blends of Zein and Nylon-6

Blends of zein and nylon-6 (55?k) in formic acid were used to produce solution cast films and electrospun fibers. When the amount of nylon-6 was 8?% or less blends were formed that had improved tensile strength and reduced solubility. The blends were analyzed using physical property measurements, DSC and IR spectra. Using between 2 and 8?% nylon-6 provided a 33?% increase in tensile strength. Young??s modulus increased by over 50?% in this range. In general elongation was lower for all formulations. Surprisingly the cast films having 0.5?C8?% nylon-6 had improved solvent resistance to 90?% ethanol/water. Electrospun fibers were produced from formic acid solutions of zein and nylon-6 where the amount of nylon was 0, 2 and 6. Fibers produced from 27?% spinning solids had average diameters on the order of 0.5???m. Reducing the spinning solids to 21?% provide slightly smaller fibers however, the fibers had more defects.     

Physical separation,mechanical enrichment and recycling-oriented characterization of spent NiMH batteries

Nickel–metal hydride (NiMH) batteries contain high amount of industrial metals, especially iron, nickel, cobalt and rare earth elements. Although the battery waste is a considerable secondary source for metal and chemical industries, a recycling process requires a suitable pretreatment method before proceeding with recovery step to reclaim all valuable elements. In this study, AA- and AAA-type spent NiMH batteries were ground and then sieved for size measurement and classification. Chemical composition of the ground battery black mass and sorted six different size fractions were determined by an analytical technique. Crystal structures of the samples were analyzed by X-ray diffraction. Results show that after mechanical treatment, almost 87 wt% of the spent NiMH batteries are suitable for further recycling steps. Size classification by sieving enriched the iron content of the samples in the coarse fraction which is bigger than 0.25 mm. On the other hand, the amounts of nickel and rare earth elements increased by decreasing sample size, and concentrated in the finer fractions. Anode and cathode active materials that are hydrogen storage alloy and nickel hydroxide were mainly collected in finer size fraction of the battery black mass.     

The use of 'exotic' framework structures in waste management

The use of porous framework materials in waste management applications has the potential to be a powerful tool in toxic metal remediation. The properties that these materials possess, including high surface area and ion-exchange capacity, are theoretically valuable. Furthermore, the flexibility of many of these frameworks allows the potential for immobilisation of waste materials with the framework of the material, in addition to the traditional capture in the pore structure. However, for either of these routes to be useful for waste management purposes, these structures must also be stable in any proposed storage media. This study examines the stability of a range of porous materials whose frameworks are made out of zinc and arsenic, both considered toxic minesite wastes, when exposed to aqueous media. The three frameworks examined (sodalite analogue Na(6)(H(2)O)(8)(ZnAsO(4))(6), open framework K(3)Zn(4)O(AsO(4))(3).3.5H(2)O, and an ABW type framework NH(4)ZnAsO(4)) all have similar hydrothermal synthetic routes and bulk framework compositions, but differ in counter ion used, pore size and complexity of structure. The phases were examined before and after storage in an aqueous environment, and their crystallinity and leaching were determined. All phases prepared were found to be extremely unstable outside their original synthetic environment, and very soluble when exposed to water, calling into question their practical use in any environment.     

Novative Biomaterials Based on Chitosan and Poly(ε-Caprolactone): Elaboration of Porous Structures

The swelling capability of chitosan was explored in order to use water both, as volatile plasticizer and as pore-forming agent. Chitosan powder was swelled in acidic aqueous solution and melt blended with poly(ε-caprolactone) (PCL). After stabilization at 57% RH and 25 °C, samples suffered a water mass loss of around 30 wt% without dimensions variation. Despite the low miscibility of these biopolymers, quite homogeneous dispersion of chitosan within the polyester matrix was obtained. Some interactions between both biopolymers could be observed. To obtain chitosan phase with a thermoplastic-like behaviour, the plasticization effect was also studied by the addition of 25 wt% glycerol as non volatile plasticizer. The equilibrium moisture content of samples increased with the incorporation of glycerol due to its hydrophilic nature. Morphology, thermal and mechanical properties of the blends were determined after stabilization. The preparation of rich PCL blends allowed the formation of macroporous structures since samples were not contracted after water loss and stabilization. These biomaterials with such a porous structure could be used for biomedical applications.     

Recycled Polyethylene Composites Reinforced with Jute Fabric from Sackcloth: Part I-Preparation and Preliminary Assessment

In recent times, environmental safety has been on priority in the development of new materials leading to a recycling and reuse approach to conserve the materials resources. This has resulted in more focus on the application of natural materials such as lignocellulosic fibers. This paper presents the characterization of continuous and aligned jute fabrics obtained from new and used sacks as well as the preparation and characterization of their composites incorporated into recycled polyethylene or as isolated pieces up to 40 wt%. These environmentally friendly composites were subjected to bend test and the fracture surface analyzed by SEM. The fabric from new sacks showed greater damage tolerance than that from the used sacks. The flexural stress increased steadily with increasing used fabric content up to 30 wt%, which is explained using fractographic studies on ruptured specimens. Used jute fabric composites are found to be viable alternative materials for low strength conventional materials based on cost–performance comparison with conventional materials.     

Cellulose–Polymer Based Green Composite Fibers by Electrospinning

Green composite fibers (339?C612?nm in diameter) have been developed from wood pulp, acetylated wood pulp and polyethylene oxide under various concentrations by electrospinning process. A polymer solution concentration of 7 wt% with 5 wt% wood pulp have been found to produce uniform composite fibers. Scanning electron microscopy micro-images demonstrated that composite fibers diameter and morphology depended on the processing parameters, such as solution concentration and molecular weight of polymer. Transmission electron microscopy and laser confocal microscopy observations indicated that the acetylated wood was well dispersed and oriented along the length of composite fibers axis. X-ray diffraction studies revealed that the structure of electrospun composite fibers became more non-crystalline.     

Synthesis and Properties of <Emphasis Type="Italic">N</Emphasis>-Maleyl Chitosan-Cross-Linked Poly(Acrylic Acid-co-Acrylamide) Superabsorbents

A high-swelling superabsorbent was synthesized with biodegradable N-maleyl chitosan as cross-linker, acrylic acid (AA) and acrylamide (AM) as the monomers, ammonium peroxodisulfate–sodium bisulfite (NaHSO₃) as redox initiation system, by means of aqueous solution polymerization. The best reaction condition was based on the orthogonal experiment design. The optimal conditions on distilled water absorbency and on 0.9 wt% NaCl solution absorbency were monomer concentration 20 wt%, mole ratio of AA to (AA + AM) 60%, the neutralization degree of AA 40%, cross-linker concentration 2% and monomer concentration 25 wt%, mole ratio of AA to (AA + AM) 60%, neutralization degree of AA 50% and cross-linker concentration 1%, respectively. Factors influencing the water absorbency of superabsorbent also were investigated, by single factor experiment method. The absorbency of superabsorbents in distilled water and 0.9 wt% NaCl solution increased and then decreased with the increasing of monomer concentration, mole ratio of AA to (AA + AM) and degree of neutralization of AA. With the increasing of cross-linker concentration, the absorbency in distilled water increased and then decreased, but it decreased all the time in 0.9 wt% NaCl solution. In enzymatic degradation tests, the weight loss of superabsorbent was related to the content of cross-linker.     

Dielectric and Material Properties of Poly (Vinyl Alcohol): Based Modified Red Mud Polymer Nanocomposites

Red mud emerges as the major waste material during production of alumina from bauxite by the Bayer??s process. Based on economics as well as environmental related issues, enormous efforts have been directed worldwide towards red mud management issues i.e. of utilization, storage and disposal. The present research work has been undertaken with an objective to explore the use of red mud as a reinforcing material in the polymer matrix as a low cost option. The silicate layered red mud was organophilized by aniline formaldehyde and to know the effect of various filler loading on the material properties of PVA-organophilized red mud composites, prepared by a conventional solvent casting technique and comparison of the same with that of the virgin poly (vinyl alcohol) (PVA), various characterizations was done. The modified red mud was typically characterized by X-ray diffraction. The X-ray diffraction pattern of the composite materials was also studied. The morphological image of the composite materials was studied by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was used to characterize the dispersion of the red mud within the composite materials. The surface topography of the composite materials was studied by Atomic Force Microscopy (AFM). The dielectric properties of composite materials were investigated in wide frequency ranges from 1?MHz to 1?GHz.     

Stiff Biodegradable Polylactide Composites with Ultrafine Cellulose Filler

Polylactide (PLA) composites with 10–30 wt% of commercial fine grain filler of native cellulose were prepared by melt-mixing, and examined. The composite films had esthetic appearance, glossy surface, creamy color and density close to that of neat PLA. Good dispersion of the filler in PLA matrix was achieved. The composites were stiffer than neat PLA; in the glassy region the storage modulus increased by approx. 30 %. The tensile strength of the composite materials in the temperature range from 25 to 45 °C was similar to that of neat PLA. No marked decrease in molar mass of PLA in the composites occurred during processing in comparison to neat PLA. Moreover, thermogravimetry experiments demonstrated good thermal stability of the composites; 5 % weight loss occurred well above 300 °C.     

A Comparison of Modified and Unmodified Cellulose Nanofiber Reinforced Polylactic Acid (PLA) Prepared by Twin Screw Extrusion

The goal of this work was to evaluate the effect of chemical modification of cellulose nanofibers (CNF) on the properties of polylactic acid (PLA) nanocomposites. Acetylated nanofibers (ACNF), with degree of substitution 1.07, were isolated from acetylated kenaf fibers by mechanical treatments. Acetylated nanofibers showed more hydrophobic properties compared to non-acetylated ones. The results showed that both crystallinity and thermal stability of acetylated nanofibers were lower than non-acetylated ones. The nanocomposites were prepared by premixing two PLA master batches, one with a high concentration of ACNF and the second with CNF. These were diluted to final concentrations (5?wt%) during the extrusion. The morphology studies of PLA and its nanocomposites showed nanofiber aggregates in both materials. The results showed that the tensile and dynamic mechanical properties were enhanced for both acetylated and non-acetylated nanocomposites compared to the neat PLA matrix while no significant improvement was observed for the acetylated nanocomposites compared to non-acetylated ones. However, the storage modulus increased slightly for acetylated nanocomposites compared to non-acetylated ones.     

Effects of Storage Time on Properties of Soybean Protein-Based Plastics

Soybean protein has been considered as a potential biodegradable polymer in the manufacture of plastics. The purpose of this investigation was to characterize the effect of storage time on thermal and mechanical properties of soybean protein isolate (SPI) plastics. SPI was separated from defatted soy flour, modified with 1M or 2M urea, or plasticized with glycerol, and compression molded into plastics. Plastic made from SPI alone was used as a control. For all SPI plastics, glass transition temperatures and dynamic storage modulus increased and loss tangent decreased during storage. Excess enthalpy of relaxation of all SPI plastics had an exponential relationship with storage time, indicating a fast aging rate at the beginning of storage. All SPI plastics tended to be stiff and brittle during storage. The plastics with glycerol had the slowest aging rate and were fairly stable after 60 days, with about 8.8 MPa tensile strength and 168% strain at break. Plastics with the 2M urea-modification SPI also had a slow aging rate and became relative stable after 60 days, with about 10 MPa tensile strength and 72% elongation.     

Characterization of Urea Encapsulated by Biodegradable Starch-PVA-Glycerol

The influence of the blending ratio of biodegradable starch/polyvinyl alcohol (PVA)/glycerol in encapsulating urea has been investigated. It is found that water absorption capacity increased approximately 135 % as the amounts of starch, PVA and glycerol in the composite film increase. Therefore, the swell ability of the composite film is increased and the urea is released from the composite film in the wet environment. The FTIR shows that the urea had been encapsulated successfully in the composite films. Moreover, the soil burial biodegradation results indicated that the biodegradability of the starch/PVA/glycerol/urea composite film strongly depended on the PVA proportion in the composite film matrix. The DSC results show that the higher the amount of PVA in the composite film, the less change of the melting enthalpy value. The crystalline region of PVA remains after biodegradation.     

Effect of Gamma Radiation on the Properties of Crosslinked Chitosan Nano-composite Film

Chitosan nano-composite film crosslinked by citric acid and with glycerol as plasticizer and MgO as antibacterial agent was prepared by casting method. MgO nanoparticles were synthesized via calcination method in furnace at 500 °C for 4 h and characterized by X-ray diffraction and transmission electron microscope. The chitosan nano-composite film with composition chitosan/citric/glycerol/magnesium oxide (1 wt%:1 wt%:75 vol%:10 wt%) has high mechanical properties than other films. The effects of different irradiation doses on the mechanical, thermal and antibacterial activity were investigated. The tensile strength enhanced by increasing irradiation dose up to 10 kGy and the elongation negligible changed as irradiation dose increased. The thermal stability slightly increased up to dose 2.5 kGy then decreased with dose increment. The antimicrobial activity film was studied against white mulberry-borne bacterial pathogens either Gram positive or Gram negative bacteria and has positive impact of gamma irradiation on the antimicrobial activity. The use of the selected chitosan nano-composite film which irradiated by dose of 2.5 kGy and has magnesium oxide of average particle size 54.3 nm as new packaging materials found to improve storage quality and shelf-life of mulberry fruit.     

Effect of Hexadecyl Lactate as Plasticizer on the Properties of Poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide) Films for Food Packaging Applications

In this study, poly(l-lactide) (PLA) films were fabricated by melt processing and the plasticizing effect of hexadecyl lactate (HL) (0, 5, 7.5, 10, and 12.5 wt% on PLA were investigated by scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis, tensile, transparency, and water vapor permeability tests. The SEM analysis revealed that PLA with 10 wt% HL appeared uniform with extra small bumps, confirmed the interaction between PLA and HL. The thermal analysis revealed a glass transition temperature of 57.4 °C for neat PLA film, but the addition of HL elicited a decrease in the temperature of the peak (43.8 °C). The incorporation of plasticizer into PLA resulted in the increase of elongation at break, as well as the decrease of tensile strength and tensile modulus. Even though a decrease in transparency was recorded, the PLA/HL blend films appeared transparent by visually observation. The water vapor permeability of PLA/HL blend films increased with the increase of HL. The PLA/HL blend films could effectively extend the shelf-life of fresh-cut pears as the commercial low density polyethylene films. The results indicated that the properties of PLA films can be modified with the addition of HL and PLA/HL blend films could serve as an alternative as food packaging materials to reduce environmental problems associated with synthetic packaging films.     

燃煤电站SNCR脱硝系统喷射还原剂介质对锅炉效率的影响

以燃煤电厂1台600MW机组配套SNCR脱硝系统为例,分别介绍了采用尿素、液氨为SNCR脱硝还原剂时,各还原剂的喷入量对锅炉效率和燃煤成本的影响。结果发现,以设计煤种Qnet,ar=11766.7kJ/kg计,当浓度5%的尿素溶液喷入时,有1.67%的燃煤发热量被水蒸发所吸收,导致排烟损失增加0.6659%。假设其他损失不变,不计固体尿素的升温、分解热反应等的影响,尿素溶液的喷入对锅炉热效率的影响在0.6659%左右,燃煤成本约增加900多万元/a;在喷入氨空混合气情况下,约0.2%的燃煤发热量被混合气所吸收,导致排烟损失增加0.02%。假设其他损失都不变,不计分解热反应等的影响,混合气的喷入对锅炉的热效率的影响亦即在0.02%左右,燃煤成本约增加30万元/a。从节能的角度看,液氨为还原剂应作为优选。     

Some Investigations on the Nylon 6/Zn Composite Material Obtained by Simultaneous Anionic Polymerization-Molding Process

This study is concerned with the behavior of samples based on nylon 6/zinc (Ny6/Zn) composite material in high salinity water that contains NaCl (3.5 wt%) and in aqueous solution of HCl (0.5 N and 1 N). The samples were obtained from parts prepared by in situ anionic ring-opening polymerization of ?-caprolactam (CL) in the presence of zinc (Zn), as filler (15 wt%) using the rotational molding technique. This type of composite was evaluated by the testing of swelling degree, structural modifications, evolution of hydrogen and electrochemical behavior. The properties of Ny6/Zn composite material have ascertained through the combined use of more analysis methods: attenuated total reflectance Fourier transform infrared spectroscopy, wide-angle X-ray diffraction technique, scanning electron microscopy, swelling and electrochemical measurements. It was revealed that regarding swelling behavior the Ny6 matrix has an important role while Zn filler contributes especially to the (electro)chemical corrosion.